Heat treating metallic conductors



July 23, 1929. G; w. ELME'N 1,722,079

` HEAT TREATING METALLIC G-ONDUGTORS Y l Filed Nv, 2o. 1922y @MAW Patented July 23, 1929.

UNITED STATES PATENT OFFICE.

GUSTAF W. ELMEN, OF LEONIA, -NEW JERSEY, ASSIGNOR '10 WESTERN ELECTRIC COM- PANY, INCORPORATED, 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK.

HEAT TREATING METALLIC OONDUCTORS.

Application led November 20, 182,2. Serial No. 602,287.

. This invention relates to the heat treatment of metals and more particularly to heat treating a signaling conductor inductively loaded with magnetic alloy. l

An object of the-invention is to provide suitable heating means for giving a moving Ametallic charge a desired heat treatment, this charge, in a narrower aspect lof the invention,

being an electric conductor in strand form.

Another object of the invention is t'o provide meansfor passing a conductor continuously through a furnace, without having its length or form varied by the forces acting upon it.

Investigations have recently been in rogress looking toward the improvement o submarine telegraph cables. As aresult of these researches it has been found that the speed of signaling over long submarine cab-lesl can be greatly increased by inductively loading the 'cable conductor with Wire or tape of a certain nickel-iron alloy applied as a spiral wrapping, the wrappedA conductor being given a certain heat treatment in order to increase the permeability of the loading material. .The preferred method of applying heat treatment #to the loaded conductor is to pass it slowly through a furnace and then through a cooling chamber. The alloy should be first brought to a temperature of about 850C or 900o C. and thenlallowved to remain at that temperature for a definite period, which appearsto be necessary to insure a uniform or proper molecular structure, after which it should be cooled slowly through the transition temperture, which is from 500" to 600 C. depending upon the composition, 'and then further :ficooled at a rate between that necessary to y-anneal and rates which would set up me- 40 chanical stresses in, the material when cold. 'For a complete description' of the 4alloy mentioned herein; the method of preparing it, its use as an inductive loading material and the mannerof applying it to the conductor to be loaded, reference is made to the following United States patents, Elmen, 1,586,884 and 1,586,887 and O. E. Buckley 1,586,874 and 1,586,875, all granted on June 1,1926.

As the sections of cable to be treated are necessarily so long and heavy that it wouldl be veryy diiicult to obtain a uniform heat treatment by applying heat simultaneously to all portions of them, either coiled or uncoiled, a method of applying a heat treatment by continuously f assing the taped conductor through a urnace and a cooling chamber has -been developed. This method is described in the abovementioned patents of Gu W. Elmen and O. E. Buckley. It has been found, however, that the furnaces described in those applications do not apply heat to the moving conductor in a manner best suited for commercial operation. According to the present invention a conductor is passed through two or more adjacent furnaces or furnace sections, the first of which `is maintained at a higher temperature than the second. It is desired to bring the alloyto a temperature considerably higher than the transition temperature and to maintain it there for a definite period, which appears to be the time necessaryto permit the molecules to rearrange themselves uniformly throughout the material. No harm would be done the conductor by maintaining it .at this temperature for a longer period, except that it is unduly softened and the shape may therefore be changed by the forces applied to move it .through the furnace, and time is lost in the operation. Since the conductor and tape are cold when they enter the furnace, heat must be applied for a considerable time to raise the tape to the desired temperature, but by heating the furnace much above that temperature the time for this required heating may be materially reduced.

Another feature of the invention has to do with feeding the loaded conductor through the furnace without elongating or shortening it. The conductor may be suficiently softened under the action of heat to permit it to be distorted. Even when the change in lengt-h is scarcely perceptible, the electrical properties of the conductor after heat treatment are varied. According to the present invention, forces applied to the conductor to move it through the` furnace and cooling chamber are so small that all danger of changing the length or form of the conductor is removed.

A complete 'disclosureof one embodiment ofthe invention is to be found in the .following specification and accompanying drawing.

Referring to the drawing, which is `diagrammatic, a taped conductor 1 is unwound from the supply reel 2, passed through the furnace 3 and cooling chamber 4 and coiled upon the receiving reel 5.. The supply reel may be 'large and heavy and not always completely balanced with respect to its bearings. Tf suicient'tension is applied to the` conductor to rot-ate the supply reel as well as to pull the conductor into and along the tube 12 tained at a temperature of vabout l850" or 900 C., and is ofsuch a length that at the perature.

velocity withwhich the conductor is moved, the latter will be maintained at this temperature the required time. The furnaces 6 and` 7 are shown, by way of example, as having electric heating coils 8 and 9, respectively, of

different size.` The two furnaces 6 and 7 are contiguous and form in effect a heating part at least of which is of magnetic alloy, .to develop a Adesired value of permeability in said alloy, comprising a heating chamber chamberwith two zones differing in tem-- The cooling chamber 4, which is illustrated as a water jacket, should be such as to cool the alloy at a rate between that necessary for annealing and rate which would set up stresses in the material when cold.

The tube 12 through which the conductor passes during the heat treatment .has a perforatioi within a jacket 10 into which is fed a'substantially non-oxidizing and non-reducing atmosphere, preferably commercially prepared nitrogenth ough the supply pipe.`

11. The-,gas enters the opening. in thetube in the jacket 10 andlowsin both directions to the two exits. This feature per se is the invention of another and is described and claimed in U. S. patent of J1 W. Harris 1,586,897, granted June 1, 1926. i

The means illustrated for carryingout the uponthe-heated conductor are kept at a'safe llow value includesva motor 13 from which "al constant drivingforce is applied to thel reel"b l y2,.'f.-"1`his vmotor likewise drives-the reel 5l -f through the variable/coupling consisting of a belt 14 andv an adjustable idling pulley `15. The driven pulley attached to the reel 5 is slightly smaller in diameter than that upon the reel 2 andthe idling pulleyl` is adjusted so that the belt 14 slips easily upon either the driving or driven pulley, there preferably l being a continual (slip yduring operation. This adjustment is such that the belt begins to slip to a greater extent wheneverthe tension applied to the conductor from the reel 5 is great enough to tend to increase the speed of the reel 2. There is at times a slight sag in the conductor between the point where it leavesthe reel 2 and where it enters the tube 12, and there may also be a slight loosening of a turn of the Conductor upon the reel 2. The reel 5 will then tend to increase its speed slightly until this slack is taken up,"afterwhich there is an immediate reduction in the speed of this reel again. It would be impracticable to drive reels 2 and 5 from the same or separate' sources of power at the same uniform rate of speed, since, as the conductor is unwound fromV one and wound upon the other,

the effective diameters of the coils andftheieley, it is obvious that they are broader than that in their application, and this has been borne in mind in claims. What is claimed is:

1. Apparatus for heat treating a conductor,

having two zones differing in temperature, a cooling chamber, a heat resisting tube extending through said heating chamber, and. .means for vpassingl said conductor through said tube at a substantially uniform rate and under forces insuiiicient to cause it to shorten or lengthen or otherwise .the heating chamber.

. 2. Apparatus for heat treating an electrical conductor having a .copper core surrounded drafting the appended change itsforin in with magnetic material, comprising a heating chamber, a cooling chamber, a heat resisting tube'extending through said heating cham er and having an internal diameter not greatly in excess of the diameterof said.

conductor, means forl feeding the conductor to said tube, means for receiving the conprovisions of this invention by which forces 55 ductor from said coolin chamber, a source ofpower for driving bot said means, and a nace bythe application of force to said conductor by said means.

3. The method of heat treating a compound conductor/comprising a copper wire surrounded by alayer ,of material in'which a desired value of-permeability is to be developed 'bysaid heat treatment, the conductor being heat treated in a furnace in which it force is suddenly materially increased, and

is passed continuously throu h a tube extendautomatically maintaining the moving force ing through the furnace, which method'comsubstantially constant. 10 f prises heating the compound conductor soon n Witness whereof, I hereunto subscribe f 5 after it enters the tube to such a temperature my name this`A 17th day of November A. D.,

' that the copper is softened to an extent which 1922. Willcause it to be deformed if the moving f GUSTAF W. ELMEN. 

